Sheet metal fastening means



I NOV. 12, M N 2,221,498

SHEET METAL FASTENING MEANS Original Filed Oct. 4, 1937 2 Sheets-Sheet l 3110mm GEORGE A.T|NNERMAN v NOV. 12,1940. T|NNERMAN 2,221,498

SHEET METAL FASTENING MEANS Original Filed Oct. 4, 1937 2 Sheets-Sheet 2 gimme WM GEORGE A- TINNERMAN Patented Nov. 12, 1940 UNITED STATES PATENT OFFICE or, by mesne assignments, to Tinnerman Products, Inc., Cleveland, Ohio, a corporation of Ohio Original application October 4, 1937, Serial No, 167,310, now Patent No. 2,150,852, dated March 14, 1939. 'Divided and this application .March 6, 1939, Serial No. 260,166 r 24 Claims.

This invention relates to improvements in the art of providing sheet metal parts with fastening means for threadedly engaging a threaded fastener, the present application being directed to such fastening means per se and is a division of prior copending application Serial Number 167,310, flied October 4, 1937 and since issued as Patent Number 2,150,852, March 14, 1939.,

Moreparticularly, this invention deals with improvements in fastening means formed in a sheet metal part and providing a self-locking thread 'into which an ordinary bolt or screw fastening may be threaded and advanced to fully tightenedposition to be automatically held in locked fastening engagement against unscrewing, displacement or otherwise working loose incident to jarring, vibration and strain set up in the members secured.

The fabrication of sheet metal structures comprising parts secured by bolt or screw iastenings threaded in such parts has heretofore been found generally inefficient and unsatisfactory in that the sheet metal parts, being relatively thin, are of insuflicient thickness to provide openings hava ing walls of suitable area with which threads of a bolt or.screw fastening may coengage to be retained effectively in applied position. In such sheet metal installations it is well known to be impracticable to tighten a threaded member in 80 an opening thus provided since the threads therearrangement overcoming .the foregoing insuf- 4o iiciencies of the prior art structures in that the elements of the fastening means so provided are suitably worked or formed, simultaneously with a novel punching operation, to have .a specific configuration providing a strengthened cross- 45 section intermediate their lengths and with the bolt engaging extremities thereof so disposed as to adapt the same for uniform threaded engagement throughout with the threads of a threaded member applied thereto. Thus, due to their 50 strengthened cross-section, the elements of the fastening means so provided, are capable of withstanding extraordinary strain and pressure in the application of the threaded member thereto, a

while the specific disposition of the bolt engaging ll extremities ensures that the same have uniform threaded engagement throughout with the threads of the threaded member in tensioned, locked engagement therewith in final applied fastening position.

. The foregoing advantages of the fastening 5 means provided by the method of the instant invention may bebest appreciated when it is considered that in certain installations in which an unhardened sheet metal part such as a panel is secured, it is often necessary or desirable to employ a hardened screw-threaded member capable of cutting its own threads in a cooperating sheet metal'part. Heretofore, it has been found that the use of hardened screws in such installations is both inemcient and impractical in that the metal of the sheet, beingrelatively soft and malleable, the areas immediately surrounding the opening receiving the screw give way easily when the inherently harder screw is drawn up to the extent that the elements comprising the screw thread engaging areas of the adjacent walls are mutilated and easily pull through onto the reverse side of the sheet thereby resulting in a loose, faulty fastening engagement.

In other installations it is often necessary to secure a member to asheet metal part made of spring metal. In such constructions the spring metal material is harder than that of the screws in which instance the fastening means provided thereintend to cut away and strip the threads of the threaded member when advanced to applied fastening position. Inasmuch as fastening elements provided in spring metalby the method of the instant invention are so formed at their extremities as to engage the threads of a bolt uniformly throughout, there is little tendency for the threads of the threaded member to become mutilated, cut away or stripped as it is tightened to locked engagement with thefastening elements.

It is therefore a primary object-of the present invention to provide a method of preparing unhardened sheet metal with a form of fastening means comprising elements so designed as to be especially adapted to withstand the extraordinary strain and drawing action of hardened screwthreaded members thereby eliminating the necessity for subjecting the sheet metal part to special treatment to harden the elements of the fastening means.

' Another primary object contemplates a method for providing in hardened sheet metal such as spring steel, a fastening means comprising ele- .mentsadapted' to engage the threads of a threaded member uniformly throughout thereby mini- 55 mizing stripping or mutilating of the threads thereof on being applied to tightened, fastening engagement.

Another object of the instant invention contemplatesthe provision in a sheet metal part, of fastening means comprising cooperating independently movable elements having wall areas of such cross-section as to provide for increased strength and rigidity throughout their lengths to withstand the axial drawing action of a threaded member applied thereto.

A further object of the invention comprehends a method by which fastening means are provided in sheet metal, in which the fastening elements thereof, at their extremities, correspond substantially to the cross-section of the threaded member ing the fastening elements or the threads of the threaded member such that they may be disassociated and again employed in the same or a similar installation.-

Further objects and advantages of the invention will be apparent to those skilled in the art as a description thereof proceeds with reference to the accompanying drawings in which like reference characters designate like parts throughout the same, and in which:

Fig. 1 is a top plan view of a sheet metal panel I or like member having fastening means provided therein by the improved method of the instant invention and comprising cooperating fastening elements receiving threaded members in uniform threaded engagement therewith;

Fig. 2 is a section'along line 2-2 of Fig. 1, looking in the direction of the arrows, showing in detail the fastening elements, provided by the improved method, in uniform threaded engagement with a threaded member throughout in applied fastening position;

Figs. 3, 4, and illustrate in plan the improved method of providing fastening means as embodied in a series of steps, Fig. 3 showing the initial step of slitting and punching an opening of specific configuration in the sheet metal part to define the fastening elements;

Fig. 4 shows the step in the method by which the fastening elements so defined, are worked longitudinally as to have a cross-section providing increased strength therein with the extremities thereof so disposed as to present an opening corresponding-substantially to the-crosssection of the threaded member;

Fig. 5 illustrates the final step in the method by which the extremities of the fastening elements are suitably shaped and trued to lie on a helix corresponding to the threads 'of the threaded member for uniform threaded engagement therewith throughout;

Figs. 6, 7, and 8 are various views of the step in the method represented in Fig. 4, Fig. 6 being an edge elevation, Fig. '7 being a. section taken on line Il, and Fig. 8 being a section taken along line 8-8, respectively, looking in the direction of the arrows;

Figs. 9, 10, and 11 are various views of the step illustrated in Fig. 5, Fig. 9 being an edge elevation, Fig. 10 being a section on line Ill-l0, and Fig. 11 being a section on line H| I respectively, looking in the direction of the arrows;

Fig. 12 shows in edge elevation the elements of a completed fastening means with a threaded member about to be applied thereto in an installation; I

Fig. 13 shows a threaded member as applied to locked fastening engagement in an installation comprising fastening elements provided by th method of the instant invention; and,

' Fig. 14 is a top plan view of an installation such as represented in Fig. 13 showing the elements of the fastening means provided by the improved method as disposed in uniform threaded engagement throughout with the threads of a bolt applied to locked fastening position; Figs. 15 to 23 inclusive show a further embodiment of the improved method for providing a modified form of fastening means, Fig. 15 representing in plan the initial step of slitting and punching an opening of specific Configuration in the sheet metal part thereby defining the fastening elements to be formed therefrom;

Fig. 16, shows in planthe step in the method by which the fastening elements so designed are worked longitudinally to have a cross-section.

providing increased strength therein and with the extremities thereof so disposed as to present an opening corresponding substantially to the cross-section of the threaded member to be applied thereto;

Fig. 17 illustrates in plan the final step of this embodiment by which the extremities of the fastening elements are suitably shaped and trued to lie on a helix corresponding to the threads of the threaded member to have uniform threaded engagement therewith throughout;

Figs. 18 and 19 are various views of the step represented in Fig. 16 of this embodiment of the method, Fig. 18 being a section on line [8-18, and Fig. 19 being a section on line l9l9 respectively, looking in the direction of the arrows;

Figs. 20, 21 and 22 are various views of'the step of the method illustrated in Fig. 17, 'Fig. 20

being a section on line 20-20 thereof, Fig. 21

being a section on line 2|-2l, and Fig. 22 being a section on line 22--22 respectively, looking in thedirection of the arrows; and,

Fig. 23 shows in edge elevation, the elements of the fastening means as completed in the step represented in Fig. 1'7, and Figs. 20 to 22 inclusive;

Figs. 24 to 29 inclusive show another embodiment of the improved method in which the fastening means comprises an additional fastening element'making for greater strength in an ins'tallation, Fig. 24 representing in plan the initial step of slitting and punching an area of a sheet metal part to define the respective fastening elements;

Fig. 25-illustrates in plan the completed fastening means as provided in this embodiment of the improved method; I

Figs. 26 and 27 are various views of the com pleted fastening means illustrated in Fig. 25, Fig. 26 being. a section taken along line 26-46, and Fig. 27 being a section taken on line 21-'-2|, respectively, looking in the direction of the arrows;

Fig. 28 shows a threaded member as applied to locked fastening engagement in an installation comprising fastening elements provided in this embodiment of the improved method, the fasengage locked fastening engagement in an installation.

comprising fastening elements provided by this embodiment of the improved method, the fastening elements being so designed as to engage three distinotthreads of the threaded member.

Fa stening means provided in sheet metal in accordance with the method of the present inve tion comprise, generally, cooperating fastening elements so formed as to coact with the thread of a threaded, member applied thereto /under tension and with progressively increasing.

/ binding actionas the member is drawn up. This binding action becomes most pronounced and positive when the threaded member is driven home to tightened fastening position to the extent thatthe fastening elements snugly engage the thread throughout and dig into and become embedded in the root of the threaded member thereby providing a locked fastening engagement from which the threaded memberucannot 'work loose under extraordinary conditions of wear, vi-

,bration and strain and over long periods of use. It. has beenfound in the art of securing sheet metal parts by bolts and screws, the mere provision of anopening in a sheet metal part to receive a threaded member is not effective to provide a fastening means in which a threaded member may be applied and drawn up as necessary to provide a tight, rigid installation. However, as by the method of this invention, if such an opening is providedin conjunction with disthreads of the threaded member;-

which are not as yieldable but which are inherently stronger and capable of withstanding any ordinary reasonable requirement which heretofore has necessitated the use of individual nuts, bolts and lock washers and-the tedious, time con- 5 suming operations vnec in the application thereofin an installation. g

Generally speaking, the added strength obtained in fastening elements provided in sheet metal by the instant method is the result of several entirely new teachings; thus, the fastening elements are each formed with a substantial corrugation throughout their lengths providing intinct elements which are struck and formed to stance it is to-be noted that the elements com-,

prising the fastening means are substantially flat or arched intermediate. their lengths, and, at their extremities present a substantially diamond shaped opening, Thus, the extremities of the fastening elements in presenting a substantial diamond opening, do not engage the thread of athreaded member throughout but only at,

spaced points; this arrangement together with the fact that the fastening elements intermediate their lengths are flat or arched and therebyread- -ily yieldable, makes for a fastening means to which, a threaded member may be quickly applied to home position in a direct axial thrust or substantial ratchet-like action and then rotated a quarter turn or more to tighten and lock in suchhome position. Such fastening means for quickly assembling and securing sheet metal parts 'arehighly advantageous for speed and economy in present day mass production and accordingly have been readily accepted by the'trade and now have'a wide range of use. However, it

thick sheet metal parts, for example, such forms strength required and accordingly it has been and necessary to sacrifice some of the aforesaid speed possible in assembling operations, but com- 75 pensate therefor byproviding fastening elements creasedstrength therein; theextremities of the fastening elements present an opening complementary to the cross-section of the threaded member for substantial line contact with 'the root diameter thereof at points substantially at right angles to its longitudinal axis; and the trued disposition of the extremities of the fastening 0 elements to lie on a helix corresponding to that of the threads of the threaded member provide for uniform threaded engagement therewith throughout. Accordingly, by the method of the present invention integral fastening means may be effectively provided in relatively heavy sheet metal parts of any size in an installation such as represented in Figs. 1 and 2 in which, for example, a panel member A provided with a series of bolt receiving means each comprising cooperating fastening elements ll, i2, may be securedas by bolts l0 passing through apertures in a supporting member B. p

Referring-more particularly to Figs 3 to 11 inclusive of the drawings, S designates a sheet metal part which may be a'fragment of any sheet metal structureinwhich it is desired to' provide fastening means to secure such part by means of,

a threaded member such as a common screw, bolt, sheet metal screw or hardened tapping screw. In the instant method for providing fastening ,means in the sheet metal part, a suitable area of the sheet S, Fig. 3, is worked as by punching an irregular, substantially egg-shaped opening I5 together with suitable slits i3,- i4, thereby defining 5 distinct, independent elements ll, i2; thus the extremities of the fastening elements or the walls stantially elliptical in form of the opening thus provided are initially, sub-- and-the opening itself is of asize substantially smaller than them) minimum cross-sectional area of the threaded member to be applied thereto. The punched and slit area thus provided defining the fastening elements, is then subjected to a'forming operation by a suitable forming die acting more particularly upon the independent fastening elements throughout their lengths to press the same out of the plane of the sheet metal part into substantial elongated corrugations ll, l8, Figs. 4 and 6 to 8 inclusive. This forming operation disposes the fastening elements il, i2 in substantially oppositely disposed relation projecting out of the plane of the sheet with each of said elements having a cross-section substantially in the form of a corrugation as shown at i8, Fig. 8. At the same time, by virtue of this corrugating operation of the fastening elements II, II, the extremities thereof are distorted from their sl1b' stantially elliptical, egg-shaped configuration I5, Fig. 3, into a circular opening [6 in plan, Fig. 4, corresponding in size substantially tothe area of the threaded member at-its root diameter. It will therefore be understood that by this forming op- V eration, the opening is not only enlarged to correspond to the minimum crossesectionalarea of throughout' the lengths of the fastening elements and disposes the same in materially projecting relation above the plane of the surrounding area of sheet metal from which'they have been deformed. Thus-the fastening eleas to engage a threaded member applied thereto on lines, substantially as at right angles to the longitudinal axis thereof such that in the operation of tightening the threaded member, the extremities of the fastening elements will more naturally tend to dig into the grooves intermediate the threads and root diameter thereof at a point removed from the plane of the sheet, thereby minimizing and practically defeating any possibility .of the same pulling through onto the reverse side of. the sheet.

The final step. in the method is disclosed. in Figs. 5 and 9 .to 11 inclusive; and this step may involve a'separate operation or be incorporated in the step described with reference to Figs. 4

- and 6 to 8 inclusive. In this step, the oppositely disposed, elements II, I! now corrugated as at l1, l8, Figs 6to 8 inclusive, are subjected to a suitable operation by which the extremities of said elements are moved from their substantially oppositely disposed relation, Fig. 6, and shaped and trued to lie on a helix corresponding to that of the threaded member to be applied thereto substantially as shown in Figs. 9 and 12. In this operation the configuration of the-truly circular opening l6, shown in plan in Fig. 5 is not disturbed but rather, only the extremities of the fastening elements are shaped to lie at definite points projecting out of the plane of the sheet S; thus the wall portion or extremity 2B of fastening .element I2 lies on a helix but evenat its lowest-point is definitely above the plane of the sheet and in such relation as to readily receive the leading thread of the threaded member in troduced thereto and thereafter coact with the opposed element Il,'the extremity IQ of which comprises the highest pointsof the helix. Since said extremities I9, 20 of the fastening elements II, l2 as'stated, present a substantially truly circular opening I6, and are also disposed on a helix corresponding to the threads of the thread- 1 ed member, they naturally are adapted to engage the bolt throughout and in uniform threaded engagement with any thread thereof at all points. Thus the maximum binding action of the extremities of the fastening. elements with the thread of the bolt is secured thereby providing, in this respect, .unusual holding ability and strength in the fastening means. Upon continued rotation of a threaded member, this uniform threaded engagement of the extremities of the fastening elements with the threads thereof becomes pronounced 'and positive in a tightened installation to the extent that the extremities tend to dig into the grooves ,intermediateadjacent threads and become embedded in the root diameter of the threaded'member in locked fastening engagement therewith.

The added strength and holding ability of fastening means provided in sheet metal by the instant method may be better understood from a, consideration of Figs. 12 to 14 inclusive showing a sheetmetal part A provided with fastening means ll, l2-and which is to be secured to 9,

I the threaded member to be applied thereto, but also provides corrugations extending substantially ,the same contacts the remaining portion of the helix defined by the extremity [9, such that in any position the said extremities I9, 20 are in uniform threaded engagement throughout with the thread of the bolt substantially as shown in Figs. 13 and 14. Further rotation of the bolt causes the fastening elements H, l2 to become tensioned and of course have a tendency to move toward the plane of the sheet, but due to the corrugated cross-section thereof, the fastehing elements are possessed of unusual inherent strength and thus tend more effectively to move toward each other and dig into the groove intermediate the adjacent threads and also embed into the root diameter of the threaded member in locked frictional, fastening engagement therewith. Thus such further rotation of the screw may be said to cause a tensioning action and progressively increasing frictional engagement between the extremities of the fastening elements and the root diameter of the bolt until the engagement thereof is such that the sheet metal member is rigidly secured and any vibration, jarring, or strain in the structure cannot cause displacement, reverse rotation or tend toward unscrewing of the bolt from applied position.

It will therefore be seen that in the instant method the fastening means provided require no special treatment other than forming and shaping. The elements may be provided in unhardened relatively thick sheet metal parts such as panels and the like, individually or in multiple, 4( to afford a most efficient securing arrangement making for extreme economy in the fabrication thereof, especiallyin mass production. The fastening means as provided by the method of the instant invention may be just as well prepared for even greater holding ability in tempered or other specially treated metal such as spring steel. In any arrangement, it will be understood that the fastening means,.above. described, may be incorporated in any sheet metal structure and enables the attachment of parts to said structure by means of threaded members which are directly threaded into the fastening means without the use of nuts or ock washers, and without possibility or likelihood of stripping the threads of the bolt or pulling the fastening elements through onto the reverse side of the sheet. Still further rigidity and locking action in an in- ,stallation may be obtained by the use of a threaded member such as a sheet metal screw having any arrangement, due to the fact that the specific fastening means provided comprise distinct independently movable'members, each fastening 7 element is capable of automatically setting. in' locked fastening engagement with the cooperating portion of the thread of the threaded member without becomin mutilated or permanently distorted to the extent that it may not again be 7 effectively employed."- Thus, the fastening elements provided as by the instant method are advantageous over any heretofore known form of similar fastening means in that they may be applied in an installation and, if desired, readily dlsassociated from the cooperating threaded member and again employed in the same or-similar installation. i

Figs. 15-23 inclusive show the method of the present invention as developed in another embodiment by which further added strength may be obtained in the fastening means provided. The method as followed with respect to this embodiment is substantially identical to that disclosed with reference to-Figs. 1-14 inclusive ex.- cept in the initial step of punching the opening l5 and slitting to define the distinct, independent fastening elements. In this form of the invention the lower fastening element l2, Fig. 15 is provided as by a-single' slit H, such that at one edge the element is integral in the plane of the I sheet S as at 30. Otherwise, the method is carried out in this embodiment substantially as described above with reference to Figs. 1-14 inclusive making due provision, of course, in the design of the forming die for the area 30 in' which the element I2 is integral. Thus, in the next succeeding step illustrated in Fig. 16, the elements I I, I! are corrugated throughout their lengths as at l8, Fig. 19 providing increased strength therein and at the same time causing the opening l5,

Fig. 15, presented by the extremities I9, 20, of the the sheet S, as shown at 30, Fig; 18. In the final step in which theextremities |9, 20, of the eleobtained 'in'the fasteningmeans provided. The method as followed in this embodiment incorporates the steps and teachings as outlined above with reference to the embodiments disclosed in Figs. 1 to 14 inclusive and Figs. 15 to 23 inclusive;

and in this respect the specific fastening elements of either of said embodiments may be included in the completed fastening means provided in this form of the invention. Generally speaking, this embodiment of the method contemplates a fastening means comprising a. plurality of distinct, independently movable fastening elements so, designed as to engage more than one thread of the; threaded member thereby pro-' viding for greater strength in an installation.

Thus, as shown in Fig. 24 in which the embodi-' tremity 42 of such element being d eiined by perforation 43. thus provided, is bent by a suitable forming operation out of 'the plane of the sheet in a return bend 44 substantially as indicated by dotted lines, Fig. 24 with the extremity 42 thereof so disposed as to liev in registration with the extremity of fastening element l2 substantially as illustrated in Figs. 25 and 26. As shown in Fig. 27, the said fastening element 40 may be'corrugated throughout its length for increased strength with the extremity" thereof suitably shaped to lie' on a helix corresponding -to that of the threads of the threaded member. Thus, as shown in Fig. 28, the basic fastening elements H, I! are provided to operate in their usual manner as described ments l H are shaped and trued to lie on a above, engaging one thread of the threaded memhelix corresponding to that of the threads of in Flg. 1'l, the trnlng of the element l2 necessarily begins at the plane of -the sheet since this ele- 'ment is integral therewith at such point. -This may be seen in Figs. '20 and 21 wherein element l2, comprising portion 20 of the helix, being integral with the sheet, rises gradually out of the plane of the sheet to a point in line "withthe remaining portion I 9 ofthe helix constituting the extremity of the cooperating fastening element method of the invention appears substantially tion of the helix lies directly in the plane'of the sheet. It'may. therefore be appreciated that in providing this form of fastening means there are several most important advantages. Thus, the

lowermost portion of the helix being directlyv in the plane of the sheet, the le 'ng thread ofthe threaded .1'nember'is inost easily engaged there- .with in a rapid, quick turning movement thereby providing for greater speed in assembling operations. However, more important is the fact that ,the element I2,"comprising the elowermost point of the helix 20, that is, that portion of the-lower fastening element which would be the first to ;tend to'pull through thesheet ondrawing up of i l the bolt,cannot possibly give way since it is in- 10 tegralwith the sheet as at 30 and thereby provided with the maximum strength possible at its most vulnerable point.

I Figs. 24-28 inclusive show; the, method of .the

instant invention as developed in a further e'm-. v

'15 bodiment in which still greater strength may be respects as illustrative and not restrictive; the 75 k I v 3 7 I, i i 1 v.

the threaded member substantially as illustrated ll', Fig. 22. Accordingly, the completed fastena .ing means presented in this embodiment of the as shown in Fig. 23, wherein the lowermost poreher In throughout; and the element 40 acts in conjunction therewith engaging the-next adjacent thread therebyproviding greater strength in the fastening means not onlyfron'i the standpoint that more than one thread of the threaded member is effectively engaged, but also, by reason ofth'e'fact that the basic fastening elements This auxiliary fastening element,

ll, 2 are relieved of a proportionate degree of stra n when thethreaded member is drawn up trated in the embodiment of Fig. 23,-engages the lowermost effective thread of the bolt, the oppo-.

sitely disposed cooperating element Ila enga es the next adjacent thread, and the auxiliary element 40a engagesthe next or third thread such that the 'strain set upin the fastening elements as the bolt is drawn up is evenly distributed and the binding action of the extremitiesthereof takes place at spaced points throughout the length of the threaded memben- While the invention has been described in'de Y tail with specific "examples, such examples are illustrative only, since it will be apparent to those skilled in the art that other embodiments within the spirit and scope of the invention may be practiced without departing from the teachings or essential characteristics thereof.;-v The present embodiments are therefore to be considered in all description, and all changes which come within the meaning and range of equivalency of the .claims are therefore intended to be embraced therein.

' What is claimed is? 1. Ina sheet metal structure, fastening means designed for self-locking threaded engagement with a threaded fastener, said fastening means comprising a thread engaging element extending out of the plane of the sheet and providing a passage for the threaded fastener, saidthread engaging element being in the form "of a substantial longitudinal corrugation extending -srub-. stantially throughout the width thereof and providing its intermediate length portion with a generally concave, transverse cross-section making for increased strength therein.

2. In a sheet metal structure, fastening means designed for self-locking threaded engagement with a threaded fastener, said fastening means comprising va thread engaging element extending out of the plane of the sheet and providing apassage for the threaded fastener, said thread engaging element being inthe form of a substantial longitudinal corrugation extending sub,- stantially throughout-the width thereof and providing its intermediate length portion with a generally concave, transverse cross-section making for increased strength therein, the end portionof said thread engaging element lying on a helix corresponding substantially to that of the threads of the threaded fastener for uniform threaded engagement therewith throughout,

with a threaded fastener, said fastening means comprising a thread engaging element extending out of ,the plane of the sheet and providing.

a passage for the threaded fastener, said thread engaging element being in the form of a sub of said thread "engaging element being of 'a shape corresponding substantially to the thread grooves about the surface of said threaded fastener.

' 4. In a sheet metal structure, fastening'means designed for self-locking threaded engagement with a threaded fastener, said fastening means comprising a thread engaging element extending out of the plane of the sheet and providing a passage for the threaded fastener, said thread -engaging element being in the form of a subments extending out of the plane of the sheet stantial longitudinal corrugation extending substantially throughout the width thereof and provi ding its intermediate length portion with ,a generally concave, transverse cross-section making for increased strength therein, the; extremity in the form of substantial longitudinal corrugaof said thread engaging element conforming sub stantially to the thread grooves about the surface of said threaded fastener and lying on a helix corresponding substantially to that of the threads of the threaded fastener f r uniform threaded engagement therewith th oughout,

5-. In a sheet metal structure, fastening means designed for self-locking threaded engagement with a threaded fastener, said fastening means comprising a plurality of thread engaging eleand providing a generally round passage for the threaded fastener, one of saldthread engaging elements being in the form of a substantial longitudinal corrugation extending substantially throughout the width thereof and-providing its intermediate length portion with a generally concave, transverse cross-section making for increased strength therein. v

6. In a sheet metal structure, fastening means designed for self-locking threaded engagement with a. threaded fastener, said fastening means comprising aplurality of thread' engaging ele-' ments extending out of. the plane of the sheet and providing a generally round passage for the threaded fastener, one of said thread engaging elements being in the form of a substantial longitudinal corrugation extending substantially throughout the width thereof and providing its intermediate length portion with a generally throughout the width thereof and providing its intermediate length portion with a generally concave, transverse cross-section making for increased strength therein, the. extremities of said thread engaging elements conforming substantially to the thread grooves about the surface of. said threaded fastener and lying on a helix corresponding substantially to that of the threads of the threaded fastener for' uniform threaded engagement therewith. a

8. In a sheet metal structure, fastening means designed for self-locking threaded engagement with a threaded fastener, said fastening means comprising a pair of cooperating thread engaging elements extending out of the plane of the sheet and providing a passage for the threaded fastener, said thread engagingelements being in theform of substantial longitudinal corrugagitudinal corrugation extending substantially tions extending substantially throughout the width thereof such that the intermediate length portion of each is of generally'concave, transverse cross-section to provide for increased strength therein.

9. In a sheet metal structure, fastening means designed for self-locking threaded engagement with a threaded fastena', said fastening means comprising a pair of cooperating thread engaging elements extending out of the plane of the sheet and providing a passage for the threaded fastener, said thread engaging elementsbeing tions extending substantially throughout the width thereof such that the intermediate length 10. Ina sheet metal structure, fastening means designed for self-locking threaded en- 75 a gagement with a threaded fastener, said fastening means comprising apair of thread engaging elements extending out of the plane of the sheet and providing a passage for the threaded engaging elements corresponding substantially to the thread grooves threaded fastenera 11. In a sheet metal structure, fastening means designed for self-locking threaded engagement with a threaded fastener, said fastening means comprising a pair of cooperating tongue elements about the surface of said extending out of the plane of the sheet and providing' therebetween a passage for the threaded of substantial longitudinal corrugations extending substantially throughout the width thereof such that the intermediate length portion of each 25 is of generally concave, transverse cross-section to provide for increased strength therein, the extremities of said to'ngue elements presenting a generally round opening corresponding substan-' tially to the thread grooves about the surface of said threaded fastener and" lying on a helix corresponding substantially to that of the threads of the threaded fastener for uniform threaded engagement therewith. 12. In a sheet metal structure, fastening means designed for self-locking threaded engagement with a threaded fastener, said fastening means comprising a thread engaging tongue element having a free edge extending out of the plane of the sheet vand providing a passage for the a segment only of said passage and being integral with the sheet in the area opposite said .free edge thereof.

13. In a sheet metal structure, fastening means with a threaded fastener, said fastening means comprising a thread engaging tongue element "having a free edge extending out of the plane of the sheet and providing a passage for the 50 threaded fastener, 'said tongue \element being integral with the sheet in the areaopposite said Y free edge thereof and being in the form of a substantial longitudinal corrugation to provide for free edge thereof and being in the form of a substantial longitudinal corrugation extending 'sub vide for increased strength therein.

15.. In a sheet metal structure, fastening means designed for self-locking threaded engagement with a threaded fastener, said fastening means comprising a thread) engaging tongue element having a free edge extending out of the plane of V 75 the sheet and providing a passage for the threaded fastener, said tongue elements being in the form.

threaded fastener,1said tongue element defining designed for self-locking threaded engagement of said I ,esta'ntially throughout the width theregf to profeistener, said tongue element being integral with the sheet in the area opposite said free edge thereof and beingin the form of a substantial longitudinal corruga'tion extending substantially throughout the width thereof to provide for increased strength therein, the exti'emity of said tongue element conforming substantially to the thread grooves about the surface of said threaded fastener and lying on a helix corresponding sub ,stantially to that of the threads of the threaded 10- fastener. V

16. In a sheet metal structure, fastening means designed for self-locking threaded engagement with a threaded fastener, said fastening means comprising a pair of cooperating threadengaging elements extending out of the plane of the sheet a and providing a passage for the threaded fas-" tener, one -of said cooperating thread engaging elements being in'the form of a substantial longitudinal corrugation to provide for increased of the plane of the sheet to engage a thread of' sheet metal structure, one of said'ton'gue elethe threaded fastener other than that engaged by said pair of cooperating thread engaging elements.

vide for increased strength therein, and a third 40 tongue element extending out of the plane of the sheet to engage a thread of the threaded fastener otherthan that engaged by said pair of cooperating tongue elements.

18. In a sheet metal structure, fastening'means designed ,for self-locking threaded engagement with a threaded fastener, said fastening means comprising a pair of cooperating thread engaging tongue elements extending out of the plane ofthe sheet and providing a ,passage for the threaded fastener, one of said tongue elements. having .a freeedge and being integral with the sheet in the area opposite said free edge thereof, one of said tongue elements being in the formof a substantial longitudinal corrugation ex-. tending substantially throughout the width thereof ,to provide for increased strength therein, said cooperating tongue elements being provided with extremitiesipresenting a generally round :opening conforming substantially to the thread grooves about the surface of said threaded fastener, anda third tongue element extending out of the plane of the" sheet to engage a; thread of means comprising. apair of cooperatingsubstantial tongue {element s struck andformed from the ments having a free edge extending-out of the plane of the sheet and being. integral with the 'sheet in the area opposite said free edge thereof.., J

20. In a'sheet metal structure, fasteningmeans designed for self-locking threaded engagement with a threaded fastener, said fastening means comprising a pairsof cooperating substantial tongue elements struckiand formed, from the sheet I metal structure, an of said tongue elements having a free edge extending out of sheet in the area. opposite said free edge thereof,

the extremity of said tongue element lying on a helix corresponding substantially to that of the threads of the threaded fastener.

22. In a sheet metal structure, fastening means designed for self-locking threaded engagement with a threaded fastener, said fastening means comprising a pair of cooperating substantial tongue elements struck and formed from the sheet metal structure, one of said tongue elements having a free edge extending out of the plane of the sheet and being integral with the sheet in the area opposite'said free edge thereof,

the extremities of both said tongue elements conforming substantially to the thread grooves about the surface of the threaded fastener.

23. In a sheet metal structure, fastening means designed for self-locking threaded engagement with a threaded fastener, said fastening means comprising a pair of cooperating substantial tongue elements struck and formed from the sheet metal structure, one of said tongue elements having a free edge extending out of the plane of \the sheet and. being integral with the sheet in thearea opposite said free edge thereof, the extremities of both said tongue elements lying on a helix corresponding substantially to that of the threads of the threaded fastener.

24. In a sheetsimetal structure, fastening means designed for selfllocking threaded engagement with a threaded fastener, said fastening means comprising a pair of\ t:ooperating substantial tongue elements struclband formed from the sheet metal structure, one of said tongue elements having a free edge extending out of the plane of the sheet and being integral with the sheet in'the areaopposite said free edge thereof, the

extremities of both said tongue elements conforming substantially to the thread grooves about the surface of the threaded fastener and lying on a helix corresponding substantially to that of the threads of the threaded fastener for uniform threaded engagement therewith throughout.

EORGE A. TINNERMAN'. 

